Chair and adjustable back support therefor



Feb. '14, 1939.

w. F. HEROLD 2,147,439

CHAIR AND ADJUSTABLE BACK SUPPORT THEREFOR Filed Dec. 2 Sheets-Sheet 1 INVENTOR \A/ALT R F HERIJLD ATTORNEY Feb. 14, 1939. Wv F O D I I 2,147,439

CHAIR AND ADJUSTABLE BAG-K SUPPORT THEREFOR- Filed Dec. 24, 1956 2 Sheets-Sheet 2 INVKENTOR X/gLTER F HERDLD ATTORNEY Patented Feb. 14, 1939 UNITED STATES PATENT OFFICE CHAIR AND ADJUSTABLE BACK SUPPORT THEREFOR Application December 24, 1936, Serial No. 117,608

2 Claims.

The present invention relates to an improved chair and adjustable back support therefor, particularly a chair in which the back is normally rigid, as distinguished from so-called posture chairs in which the back is yieldably supported by spring means for tilting movement. This application is a continuation in part of my application for Posture chair, Serial No. 93,351, filed July 30, 1936 matured into Patent 2,093,319 issued Sept. 14, 1937.

The invention has for an object to provide adjustment means by which the back may be easily adjusted to any desired position with respect to the seat so that the particular user of the chair may exactly adapt the back conforming shape of the chair back to the size and curve of his body to obtain the desired comfort, support and sitting posture. The invention is especially adapted for use in connection with a-chair of the swivel and tilting type, and which permits the back to be adjusted in relation to the tilting axis so that the weight and center of gravity of the particular person may be properly disposed with respect to the tilting axis to insure easy and properly balanced tilting movement of the chair.

It is particularly proposed to provide an adjustment support for the back, having a pivotally mounted lever which may be adjusted to vary the height of the back with respect to the seat, and also having a lever pivotally mounted upon the first lever whereby the angle of the back may be adjusted, the adjustment of one lever compensating for the adjustment of the other, so that the back may be disposed in any desired angular position at any desired height.

It is an object to provide such means, which reliably support the back in adjusted position without slippage and which may be easily and conveniently operated to adjust the height and angularity. To this end it is proposed to provide in each of the adjustable levers-a slot disposed in non-concentric relation to the axis about which the lever moves, in each of which slots is engaged a bolt which engages a slot in the supporting structure of the lever and also disposed in nonconcentric relation to the axis, the arrangement being such that the slots engage the bolt with a scissor-like gripping action, which while permitting convenient angular adjustment of the levers in the unsecured relation of the bolt will rigidly support the back against movement upon tightening of the bolt.

Due to the scissor-like gripping action of the slots upon the bolts only a relatively slight friction is required in the securing of the bolt, so

that the latter may be secured by a comparatively easy and slight turning of the hand nut upon the bolt, as distinguished from certain previous types of adjusting means in which the bolt engages slotted means concentric to the axis about which the adjustment is made, and in which the whole securing action depends upon the axial tightening of the bolt.

With the above and other objects in view an embodiment of the invention is shown in the accompanying drawings, and this embodiment will be hereinafter more fully described with reference thereto, and the invention will be finally pointed out in the claims.

In the drawings:

Fig. 1 is a side elevation of the back supporting mechanism, according to the invention, portions of the chair seat and chair back being secured thereto.

Fig. 2 is a plan view with the seat removed.

Fig. 3 is a vertical sectional view, taken along the line 3-3 of Fig. 1.

Fig. 4 is a side elevation of a chair, according to the invention, the chair seat being shown with arms attached thereto.

Fig. 5 is a similar view showing the mechanism adjusted to both lower the back and move it forwardly, this illustration showing the back provided with arm supports.

Similar reference characters indicate corresponding parts throughout the several figures of the drawings.

As seen in Figs. 4 and 5 the chair seat Ill is provided at its under side with the usual spider arms ll, between which is disposed the bearing post member 12 swivelly mounted upon the base 13 in the usual manner, and upon which the spider arms are mounted for tilting movement about the shaft I4. These parts are of well known construction and operation, and may be of any of the usual commercial types.

The back supporting mechanism, according to the invention, is mounted upon the under side of the chair seat rearwardly of the shaft l4 and at each side of the spider arms and comprises angle iron brackets I5-l5 secured to the chair seat by means of screws or the like It engaged through countersunk holes ll in the upper sides of the brackets. The brackets are disposed in parallel relation to each other and upon the outer sides of each of them and adjacent the forward edges there is pivotally secured by means of a riveted stud l8 a lever 19 extending rearwardly beyond the rearward edge of the bracket, and having pivotally mounted upon its rearward portion adjacent its upper edge by means of a riveted stud 20 a rearwardly extending lever 2|, the end of which is bent inwardly, as at 22, to form a flange upon which the cross piece 23 at the lower end of the back 24 is secured by means of rivets 25.

It will be noted that the lever I9 is substantially longer than the lever 2| and normally extends in substantially horizontal direction, and that the combined length of the levers l9 and 2| provide a substantially long lever arm pivotally supporting the back upon the pivot studs l8, the adjustment of this arm by pivotal movement about the studs I8, as will presently more fully appear, afiecting the height adjustment of the back, the angle adjustment being affected by relative pivotal movement of the lever 2| with respect to the levers l9.

In each of the bracket members I5 there is provided near the rearward end an elongated inclined slightly arcuate slot 26 disposed in nonconcentric relation to the pivot stud I8, and in each of the lever members Hi there is provided a straight slot 21, preferably arranged along a radial line of the stud 8, and disposed in intersecting angular relation to the slot 26. A bolt 28 is engaged through the slots 26 and 21, being provided upon one end with a head 29 engaged with the outer surface of the bracket member l5 at one side, and provided adjacent its head with a squared portion 30 engaged in the slot 2'! of the lever member at one side to prevent relative turning movement of the bolt, the other end of the shaft being threaded and extending through the slots 26 and 21 at the other side where it is engaged by an interiorly threaded hand nut 3|, a spanner sleeve 32 being engaged upon the bolt between the inner sides of the bracket members |5--|5. A washer 33 is preferably provided between the inner end of the hand nut 3| and the outer surface of the lever member l9.

Upon tightening of the nut 3| a clamping action: is set up between the head 29, the sleeve 32, and the washer 33 axially of the bolt, which frictionally binds or clamps the sides of the lever members |9|9 and the brackets |5-|5 with respect to each other, a scissor-like binding action being also set up upon the bolt 28 producing a moment of resistance against relative movement between the bracket members and the lever members, which in addition to the binding action set up upon tightening of the nut 3| rigidly secures the parts against movement.

The arrangement of the double slots is such, when pressure is applied against the back in the tightened or locked relation of the parts, that the axial clamping action only takes a portion of the torque or moment around the axis of the pivot studs IS, the resultant being taken by the scissor action between the slots and the bolt. As only a slight axial clamping action is required to prevent relative movement of the bolt in the slots the nut 3| does not have to be tightened with much force and may therefore be operated with comparative ease.

However upon loosening the nut 3| and releasing the binding action there is, as the back is adjusted upwardly and downwardly, a camming action set up between the slots 26 and 21 and the bolt 28 causing the bolt to move in one or the other direction in the slots. As shown in Fig. 5 the back has been adjusted downwardly and its bolt has moved from substantially the central portions of the slots to the left hand ends of the slots. In adjusting the back upwardly the movement of the bolt will be in the opposite direction to the right hand ends of the slots. It will be understood that during this raising and lowering adjustment the angle adjustment means is rigidly connected to the lever I9, and as above pointed out the levers 2| form extensions to these levers |9 increasing the length of the lever arm.

The connection of the levers 2|-2| with the levers lE-IQ is substantially similar to the connection of the levers |9-|9 with the brackets |5--|5, and consists in the provision of an elongated inclined slightly arcuate slot 34 in each of the levers 9|9 rearwardly of the brackets I5, a straight slot 35 in each of the levers members 2|--2| preferably disposed along a radial line of the pivot studs 2020 and disposed in intersecting angular relation of the slot 34. A bolt 36 is engaged through the slots having a head 31 at one end engaging the outer surface of the lever member 2! at one side, and provided with a squared portion 38 adjacent the head engaging the slot 35 of said lever to prevent relative turning movement of the bolt, the other end of the bolt being threaded and engaged by an interiorly threaded hand nut 39, a spanner sleeve 40 being engaged upon the bolt between the inner surfaces of the lever members lSl-H, and a washer member 4| being disposed upon the bolt between the hand nut 39 and the outer surface of the lever member 2|. The action of this adjusting means is similar to the adjusting means for the levers |9|9, the hand nut being loosened when it is desired to adjust the angle of the back and the adjustment being fixed upon tightening of the hand nut, it being understood that this adjustment is preferably accomplished while the lever members |9i9 are secured rigidly.

As shown in Fig. 2 the bolts 28 and 36 are arranged to extend in opposite directions, so that one hand nut is at one side and the other hand nut is at the other side. Because of this arrangement, and also because of the ease with which the parts may be adjusted, a person seated in the chair may operate one adjustment with one hand and the other adjustment with the other hand simultaneously.

As shown in Fig. 4 the chair seat 20 is provided with arm rests 42 which are not connected with the back, so that the latter may have free adjustment movement with respect to the seat and arm rests, and in Fig. 5 the back 24 is provided with arm rests 43 which move with the back, and therefore permit re-adjustment of the back and arm rests with respect to the seat. In both cases the back supporting mechanism and its operation are the same.

I have illustrated and described a preferred and satisfactory embodiment of the invention, but it will be understood that changes may be made therein within the spirit scope thereof as defined in the appended claims.

Having thus described my invention what I claim and desire to secure by Letters Patent is:

1. An adjustable support for a chair back comprising a supporting means adapted to be rigidly secured to a part of the chair, lever means pivotally secured to said supporting means extending in a generally horizontal direction and adapted to have pivotal movement in an arc disposed in a generally vertical direction, a second lever means pivotally secured to said first lever means forming an extension thereof extending rearwardly therefrom in a generally horizontal direction to substantially increase the length of the eifective lever arm of said first lever means and adapted to have pivotal movement in an arc disposed in a generally horizontal direction, said second lever means adapted to have the chair back secured thereto with said chair back extending in a generally vertical direction, releasable securing means disposed between the pivotal axes of said first and second lever means at a point substantially removed from the pivotal axis of said first lever means and in proximity to the pivotal axis of said second lever means arranged to adjustably and rigidly secure said. first lever means to said supporting means, and releasable securing means operable independently of said first securing means arranged to adjustably and rigidly secure said second lever means to said first lever means, said releasable securing means of said first and second lever means adapted when released to permit free movement of said lever means about their supporting axes throughout their swinging ranges.

2. An adjustable support for a chair back comprising supporting means adapted to be secured to a part of the chair, a lever means pivotally secured to said supporting means, said supporting means and said lever means each having a slot, one of said slots being at an angle to the other slot and both of said slots being nonconcentric to the pivotal axis of said lever means, a bolt engaged in said slots, and clamping means operable axially of said bolt for clamping said supporting means and lever means together, a second lever means pivotally secured to said first lever means and adapted to have the chair back secured thereto, said first lever means and said second lever means each having a slot, one of said slots being at an angle to the other slot and both of said slots being nonconcentric to the pivotal axis of said second lever means, a bolt engaged in said slots, and clamping means operable axially of said belt for clamping said first and second lever means together.

WALTER F. HEROLD. 

